Position two racks in the upper and lower thirds of the oven. Line two large-rimmed baking sheets with parchment paper.

In a large bowl, whisk together the confectioners’ sugar, cocoa powder, salt, chopped hazelnuts and chocolate chips. Add the egg whites and vanilla extract , and whisk until well combined. Do not overbeat or it will stiffen. Stir in chocolate chips

Spoon a generous tablespoon of batter onto the baking sheets, 5 per sheet, leaving 3 inches between each mound so that they have room to spread. If there is additional batter, wait until the first batch comes out of the oven before scooping the rest of the cookies.

Bake for 14 to 16 minutes, until the tops are glossy and lightly cracked; shift the pans from front to back and top to bottom halfway through to ensure even baking.

Slide the parchment paper (with the cookies) onto 2 wire racks. Let cookies cool completely, and store in an airtight container for up to 3 days.